Novel dendrite-patterned triangles of Y4O(OH)9NO3:Eu3+ have been successfully prepared via a simple hydrothermal method without using any surfactant, catalyst, or template. The growth mechanism was interpreted as a modified diffusion-limited aggregation (DLA) model. Detailed contrast experiments revealed that the regulation of ethylene glycol/water ratio and pH value was essential for the formation of dendrites. The ethylene glycol served multiple functions in the formation of dendrites: to bind with Y3+ ions, change the viscosity of reaction solution, and selectively adsorb on certain faces of crystals. The as-formed precursors could transform into Y2O3:Eu3+ hierarchical dendrites after calcination, which exhibited strong red emission under ultraviolet excitation. Furthermore, the dependence of the luminescence performance on different morphologies was discussed in detail.
